A γ,δ-unsaturated alcohol has a double bond and a hydroxyl group in a molecule thereof, and by converting the respective functional groups, it can be converted into a variety of organic compounds. Therefore, the γ,δ-unsaturated alcohol is an extremely useful compound in the field of organic synthetic chemistry.
As one of production methods of the foregoing γ,δ-unsaturated alcohol, there is known a method of subjecting an α-olefin of every sort and kind and an aldehyde to thermal reaction in the absence of a catalyst. For example, PTL 1 and NPL 1 disclose a method of allowing an α-olefin and an aldehyde to react with each other at 100 to 250° C. for 2 to 16 hours under a high pressure of 200 atm (20 MPa) or more.
A problem of this reaction resides in the matter that the formation of an acid is caused due to disproportionation of an aldehyde (see PTL 2), namely in the case of using formaldehyde, formic acid is formed. The acid, such as formic acid, not only causes corrosion of an apparatus but also reacts with a γ,δ-unsaturated alcohol to form an ester during the reaction or purification, thereby decreasing the yield of the γ,δ-unsaturated alcohol. Furthermore, the foregoing ester is included into the γ,δ-unsaturated alcohol at the time of purification by distillation, thereby causing deterioration of purity or quality of products.
As a method of solving the aforementioned problem, PTLs 2 and 3 recommend a method of carrying out the aforementioned reaction in the presence of a basic compound, such as ammonia, hexamethylenetetramine, etc. In PTL 4, an α-olefin and an aldehyde are allowed to react with each other using a phosphate as the basic compound at −20 to 320° C. and at 100 to 250 atm (10 to 25 MPa), whereby a γ,δ-unsaturated alcohol is obtained in a relatively good yield. But, the methods of PTLs 2 to 4 involve such a problem that in the case of performing the reaction in the absence of a basic compound, a thorough industrial yield is not obtained. In addition, in the case of using a nitrogen-containing compound as the basic compound, there is involved such a problem that a minute amount of the decomposed nitrogen-containing compound is included into a product. In addition, in the method using a phosphate as in PTL 4, though no inclusion of the phosphate into a product occurs, there is caused such a fault that the phosphate with low solubility is deposited in a reactor or a piping, thereby causing clogging of the piping.
Then, PTL 5 discloses that taking the aforementioned problem of PTL 3, in a method of carrying out the reaction of an α-olefin and formaldehyde in the presence of a solvent at 150 to 350° C. and at 30 to 500 atm (3 to 50 MPa), by adopting an alcohol having 3 to 10 carbon atoms as a solvent and using the solvent in an amount of 2 to 20 molar times to formaldehyde in a formalin aqueous solution, even if the reaction is performed in the absence of a basic compound, the formation of a by-product can be inhibited. According to the foregoing method, a product is obtained in a selectivity of about 91% at maximum.